Many countries censor the Internet, but few spell out their intentions as explicitly as Pakistan.

In an effort to tighten its control over the Internet, the government recently published a public tender for the “development, deployment and operation of a national-level URL filtering and blocking system.”

Technology companies, academic institutions and other interested parties have until March 16 to submit proposals for the $10 million project, but anger about it has been growing both inside and outside Pakistan.

Censorship of the Web is nothing new in Pakistan, which, like other countries in the region, says it wants to uphold public morality, protect national security or prevent blasphemy. The government has blocked access to pornographic sites, as well as, from time to time, mainstream services like Facebook and YouTube.

Until now, however, Pakistan has done so in a makeshift way, demanding that Internet service providers cut off access to specific sites upon request. With Internet use growing rapidly, the censors are struggling to keep up, so the government wants to build an automatic blocking and filtering system, like the so-called Great Firewall of China.

While China and other governments that sanitize the Internet generally do so with little public disclosure, Pakistan is being surprisingly forthcoming about its censorship needs. It published its request for proposals on the Web site of the Information and Communications Technology Ministry’s Research and Development Fund and even took out newspaper advertisements to publicize the project.

“The system would have a central database of undesirable URL’s that would be loaded on the distributed hardware boxes at each POP and updated on daily basis,” the request for proposals says, referring to uniform resource locators, the unique addresses for specific Web pages, and points of presence, or access points.

“The database would be regularly updated through subscription to an international reputed company maintaining and updating such databases,” according to the request, which was published last month.

The tender details a number of technical specifications, including the fact that the technology “should be able to handle a block list of up to 50 million URL’s (concurrent unidirectional filtering capacity) with processing delay of not more than 1 milliseconds.”

Following the Arab Spring, which demonstrated the power of the Internet to help spread political and social change, Pakistan’s move to clamp down has set off a storm of protest among free-speech groups in the country and beyond.

Opponents of censorship say they are doubly appalled because they associated this kind of heavy-handed approach more with the previous regime of Gen. Pervez Musharraf than with the current government of President Asif Ali Zardari.

“The authorities here are big fans of China and how it filters the Internet,” said Sana Saleem, chief executive of Bolo Bhi, a group that campaigns against restrictions on the Internet. “They overlook the fact that China is an autocratic regime and we are a democracy.”

“What makes this kind of censorship so insidious is that they always use national security, pornography or blasphemy as an explanation for blocking other kinds of speech,” Ms. Saleem said, adding that her site had been blocked for several months in 2010 when it made reference to a ban on Facebook. Access to the social networking service had been restricted because of a page featuring a competition to draw the prophet Mohammed — something that is considered blasphemous by Muslims.

The Technology Ministry’s Research and Development Fund says in its tender that the Internet filtering and blocking system will be “indigenously developed,” but campaigners like Ms. Saleem say they think it is likely the agency will try to adapt Western technology for the purpose.

To try to prevent this from happening, Ms. Saleem wrote to the chief executives of eight international companies that make Net filtering technology, asking them to make a public commitment not to apply for the Pakistani grant.

On Friday, one of them, Websense, which is based in San Diego, responded, declaring in a statement on its Web site that it would not seek the contract.

“Broad government censorship of citizen access to the Internet is morally wrong,” Websense said. “We further believe that any company whose products are currently being used for government-imposed censorship should remove their technology so that it is not used in this way by oppressive governments.”

Websense had previously withdrawn the use of its technology from Yemen after facing accusations from the OpenNet Initiative, a U.S.-Canadian academic group, and other organizations that it had been used by the government of that country to stifle political expression on the Internet.

Governments around the world buy filtering and blocking technology to root out illegal content like child pornography. Some private companies employ it to restrict access to social networks and other distractions on company computers.

But the use of Western technology to rein in political speech in countries with repressive regimes has come under increasing scrutiny since the Arab Spring. The OpenNet Initiative said in a report last year that at least nine governments in the Middle East or North Africa had used such products, with the Western companies maintaining lists of sites to be blocked, including sites featuring skeptical views of Islam and even dating services.

Even before implementing its new system, Pakistan has been an active censor. The country was 151st, out of 179, on a ranking of media freedom by the Paris-based group Reporters Without Borders in 2011.

“Reporters Without Borders urges you to abandon this project, which would reinforce the arsenal of measures for communications surveillance and Internet censorship that have already been put in place by your government,” the group wrote in a letter Friday to Prime Minister Yousaf Raza Gilani.

To free-speech advocates in Pakistan, the government’s seeming insouciance about censorship is a particular cause for alarm.

“This is a case study,” said Ms. Saleem of Bolo Bhi, which is based in Karachi and whose name means “speak up.” “No government has ever done this so publicly.”